Why are writes failing in MongoDB?

Here is the information about my development environment:

• Microsoft Visual Studio Community 2015
• .NET Framework 4.6
• ASP.NET
• MVC assembly System.Web.Mvc Version=5.2.3.0
• MongoDB.Driver 2.0.1.27
• Mongodb 3.0.6

From my ASP.NET C# application, I have code that writes to a MongoDB database.

Here is an excerpt from the logging shown by MongoDB after I started it in DOS command Prompt(From my analysis of the log shown below, it seems that a write to the database has occurred):

C:Program FilesMongoDBServer3.0bin>mongod --dbpath ./data/db
2015-09-25T14:18:04.567+0530 I JOURNAL  [initandlisten] journal     dir=./data/dbjo
urnal
2015-09-25T14:18:04.571+0530 I JOURNAL  [initandlisten] recover : no     journal fil
es present, no recovery needed
2015-09-25T14:18:05.120+0530 I JOURNAL  [durability] Durability thread     started
2015-09-25T14:18:05.122+0530 I JOURNAL  [journal writer] Journal writer     thread s
tarted
2015-09-25T14:18:05.297+0530 I CONTROL  [initandlisten] MongoDB starting :     pid=8
532 port=27017 dbpath=./data/db 64-bit host=My-PC
2015-09-25T14:18:05.298+0530 I CONTROL  [initandlisten] targetMinOS:     Windows 7/W
indows Server 2008 R2
2015-09-25T14:18:05.299+0530 I CONTROL  [initandlisten] db version v3.0.6
2015-09-25T14:18:05.299+0530 I CONTROL  [initandlisten] git version:     1ef45a23a4c
5e3480ac919b28afcba3c615488f2
2015-09-25T14:18:05.300+0530 I CONTROL  [initandlisten] build info: windows     sys.
getwindowsversion(major=6, minor=1, build=7601, platform=2,     service_pack='Servic
e Pack 1') BOOST_LIB_VERSION=1_49
2015-09-25T14:18:05.301+0530 I CONTROL  [initandlisten] allocator: tcmalloc
2015-09-25T14:18:05.302+0530 I CONTROL  [initandlisten] options: { storage:     { db
Path: "./data/db" } }
2015-09-25T14:18:05.357+0530 I NETWORK  [initandlisten] waiting for     connections
on port 27017
2015-09-25T14:19:25.218+0530 I NETWORK  [initandlisten] connection accepted     from
 127.0.0.1:64412 #1 (1 connection now open)
2015-09-25T14:19:36.317+0530 I NETWORK  [initandlisten] connection accepted     from
 127.0.0.1:64416 #2 (2 connections now open)
2015-09-25T14:19:38.761+0530 I COMMAND  [conn2] command foo.$cmd command:     insert
 { insert: "Users", ordered: true, documents: [ { _id: 0, UserName: "blah",     Pass
word: "blahb", Email: "blha", PhoneNo: null, Address: null } ] }     keyUpdates:0 wr
iteConflicts:0 numYields:0 reslen:166 locks:{ Global: { acquireCount: { r:     1, w:
 1 } }, MMAPV1Journal: { acquireCount: { w: 2 }, acquireWaitCount: { w:     1 }, tim
eAcquiringMicros: { w: 38 } }, Database: { acquireCount: { w: 1 } },     Collection:
 { acquireCount: { W: 1 } } } 128ms
2015-09-25T14:22:01.148+0530 I NETWORK  [conn1] end connection     127.0.0.1:64412 (
1 connection now open)
2015-09-25T14:22:01.149+0530 I NETWORK  [conn2] end connection     127.0.0.1:64416 (
1 connection now open)
2015-09-25T14:22:54.252+0530 I NETWORK  [initandlisten] connection accepted     from
 127.0.0.1:64537 #3 (1 connection now open)

Using another DOS Command Prompt, I ran the client Mongo in order to query the database:

C:Program FilesMongoDBServer3.0bin>mongo

MongoDB shell version: 3.0.6

connecting to: test

> use foo

switched to db foo

> db.Users.find()

{ "_id" : 
0, "UserName" : "quit", "Password" : "end", "Email" : "exit", "PhoneNo

" : null, "Address" : null }

> db.runCommand( { getLastError: 1, w: 1, wtimeout:5000 } )

{

     "connectionId" : 4,

     "n" : 0,

     "syncMillis" : 0,

     "writtenTo" : null,

     "err" : null,

     "ok" : 1

}

>

Based on the query results from the client Mongo, it seems the write to the database occurred.

Why is the MongoDB log stating that a write occurred, but the client Mongo fails to show any write occurred?
Also, could someone please tell me how to ensure that the entry gets written to MongoDB?

The problem was in my C# Model POCO class code. ( https://stackoverflow.com/questions/32733038/why-is-c-sharp-and-mongodb-driver-code-connecting-but-failing-to-write/32798031#32798031 )

It took a while, but the problem was caused by the fact that I mistakenly used the int basic data type for the ID in the UserModel as opposed to ObjectId.

Here is the corrected code for the UserModel:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Web;
using System.ComponentModel.DataAnnotations;
using System.Web.Mvc;
using MongoDB.Bson;
using MongoDB.Driver;
using MongoDB.Driver.Linq;
using WebApplication1.Models;
using MongoDB.Bson.Serialization.Attributes;

namespace WebApplication1.Models
{
    public class UserModel
    {

        [BsonId]
        public ObjectId ID { get; set; }

        [Required]
        [BsonElement]
        public string UserName { get; set; }

        [Required]
        [BsonElement]
        public string Password { get; set; }

        [Required]
        [BsonElement]
        public string Email { get; set; }

        [BsonElement]
        public string PhoneNo { get; set; }

        [BsonElement]
        public string Address { get; set; }
    }
}